Airlines commonly use data processing and telecommunications equipment for communicating with their airplanes. Prior art proposals suggest the use of portable navigational planning systems that create charts for use by pilots. U.S. Pat. No. 4,827,419 to Selby which issued May 2, 1989, is an example of a prior art proposal for a system for retrieving data from a database for use as a navigational aid. Air navigation flight charts may be printed on board the plane in conjunction with a trip confirmation and an FAA flight plan. The Selby patent suggests use of a thermal printer having a high-resolution printhead for printing charts having a size of approximately 51/2".times.8". The '419 patent describes the printer as being non-crucial to the operation of the database information conveying system and any commercially available printer is suggested for use.
A mobile printer presents issues of reliability, maintainability and use not encountered in the design of a stationary printer permanently attached to the output of a stationary computer. The mobile printer must be easy to use and able to withstand the demanding operating conditions encountered during flight. Additionally, the mobile printer must be able to convey information from multiple sources. If all data is generated and/or stored within the printer and/or a computer attached to the printer, standard techniques of transmitting that data to the printhead are appropriate. If, however, the data is derived from multiple sources including sources remotely located from the mobile printer, the printer control mechanism must accommodate the telecommunications protocols used in conveying the information.
The suggestion in the '419 patent to Selby that a standard printhead and interface between printer and computer may be used may be true for the database system disclosed in the '419 patent. It is believed, however, that this suggestion is too simplistic an approach for an efficient, reliable mobile print system.